Photonic effects in the deactivation of ion implanted arsenic

Observation has been made of a photonic enhancement effect during optical rapid thermal annealing (RTA) of high dose, As implants in Si. Arsenic implant activation using optical radiation heating from tungsten-halogen lamps, λpeak=0.8 μm, was compared with annealing in a continuously heated rapid thermal vertical furnace, λpeak=2 μm. Energetic photons assist in the rapid deactivation of electrically active As+ to its equilibrium value in less than 5 s at the annealing temperature of 1000 °C. A model is presented for rapid As deactivation which is based upon the lowering of reaction energies through electron/hole recombination events. Transient-enhanced diffusion is observed in the RTA sample but not in the furnace-annealed sample. Rapid deactivation by recombination-enhanced processes causes the generation of excess self-interstitials of sufficient concentrations to contribute to the growth of end-of-range dislocation loops at the original amorphous/crystalline interface. After deactivation ends and the excess self-interstitials dissipate, the loops are able to dissolve and coarsen, thereby emitting self-interstitials which cause As transient-enhanced diffusion (TED) in the lower concentration portions of the RTA-annealed As profile. By contrast, end-of-range loops in samples similarly annealed in the vertical furnace are somewhat smaller but of higher density, and a 1000 °C, 15 s anneal results in As deactivation overshoot where [As+] drops below the electrical solubility limit. No As TED was observed in this sample due to the absorption of excess self-interstitials by the growing loops over the duration of the anneal. © 1998 American Institute of Physics.

Duke Scholars

Author Richard B. Fair Electrical and Computer Engineering